When Elham, an asylum seeker from Iran who was 13 weeks pregnant, complained of pain, nurses and doctors told her there was nothing wrong. When she asked for an ultrasound “to see how is my foetus”, she was told there was no ultrasound on Christmas Island.

“But unfortunately one night about 8pm my pain came on again and made me shout very loudly and I couldn't tolerate it anymore,” she said.

“I was going unconscious sometime and I got bleeding – and even with this situation they didn't pay attention to me and told me it's normal, no need to go to hospital.”

Elham told Guardian Australia that one of the detention staff, taking pity on her, had driven her to hospital. An ultrasound revealed she had miscarried. She says her husband was told at the hospital the baby might have been saved “if they could bring your wife earlier”. This happened in September.

Weeks later Elham contacted Guardian Australia because, she says, she had been given no further ultrasound to find what had gone wrong. “Every time I am asking them, they keep telling me that you are in detention centre and should not expect a lot.”

The 15 doctors whose “letter of concern” has been reported exclusively by Guardian Australia put failures of antenatal care among the most serious of the “unsafe practices and gross departures from generally accepted medical standards” experienced by asylum seekers on Christmas Island.

The president of the Australian Human Rights Commission, Gillian Triggs, told Guardian Australia on Monday that the doctors report was “chilling in its objective scientific clarity” and reinforced her belief that “Australia appears to fail to meet international legal standards of humane treatment of asylum seekers”.

When doctors arrive on Christmas Island they are told that antenatal care is to be provided to detainees as per “standard practice”. But the 15 doctors say the care offered by their employer, International Health and Medical Services, “is unsafe and inadequate and does not comply with Australian standards.”

Ultrasounds are a big problem. The island’s hospital has a machine but the doctors say there are rarely specialists available who know how to use it. Ultrasonographers visit the island only every few months and, according to the doctors, they “cater primarily for local residents”.

Women like Elham who may miscarry are put at risk. So are women who may need a termination. The doctors write of the helplessness of women who conceive soon after being given live vaccines or face other reasons for needing to assess the risk of carrying a foetus to term.

A woman known as C14 was “very distressed that her child may have foetal abnormalities. She was considering a termination. Specialists advised ultrasound morphology scan and specialist review. No ultrasound was provided and she was not transferred for review. She has now passed the point where a termination is likely. Her situation has resulted in considerable distress.”

When Labor revived the “Pacific solution” in 2012, pregnant women were not sent to Nauru. But the new Coalition government operates under a “no exceptions” rule that means all asylum seekers who have arrived at Christmas Island since mid-July – even women with high-risk pregnancies – are sent to the immigration detention centre on Nauru.

"The previous government sent very few people to Manus Island and Nauru for offshore processing because they didn't really believe in it,” the new minister for immigration, Scott Morrison, said in October. “The difference between the Coalition government and Labor is that the Coalition is actually implementing offshore processing properly."

The pregnancy of a 30-year old Rohingyan woman known as Latifa was assessed by doctors on Christmas Island as “very high risk”. She had a history of caesareans and was thought to be carrying twins. Despite this she was sent by the Abbott government to Nauru where she was expected to give birth.

Guardian Australia broke that story in October. The doctors allege they were told the political objectives of the Department of Immigration and Border Protection outweighed their concern for Latifa. They write: “IHMS management stated to staff the DIBP were ‘setting an example’.”

In the end, Latifa had to be flown to Brisbane to give birth. There it was found she was not carrying twins but her baby remained in hospital for some weeks with respiratory problems. She was locked in immigration detention, unable to be with her child at night. According to press reports the boy’s father was not allow to visit the hospital at all after the birth.

Latifa’s child Farus has joined more than 1500 asylum seeker children in detention. The doctors on Christmas Island have called for an immediate end to this and charge IHMS with the failure to advocate for the immediate removal of children from detention.

“IHMS appears complicit in plans to detain children and adolescents on Christmas Island long term (indefinitely),” the doctors write. This is despite “warnings from key medical bodies such as the Royal Australasian College of Physicians regarding the likely consequences of prolonged detention in this vulnerable group”.

The doctors condemn the confiscation of medications, glasses and hearing aids from children when they arrive on Christmas Island. “This results in numerous children within the camp living with visual/hearing impairment.”

They condemn “minimal preventative care and no regular monitoring of child health”. They claim dental services for children are at best “variable” and claim there are “none of the scheduled physical and developmental assessments that would normally occur in the community (typically by a maternal child health nurse), occur at Christmas Island.”

Perhaps their most scathing criticism is reserved for the failure of Australian authorities to put in place systems to deal with the known impact of prolonged detention on the mental health of young detainees.

“Children within the camp have demonstrated signs of acute stress including enuresis [bed wetting] and marked behaviour changes,” the doctors write. “However, despite this evidence there are no effective systems in place for detecting children at risk.

“Furthermore, there are no child-specific mental health services on the island (ie no paediatric psychologist or psychiatrist).”

IHMS declined to address issues raised in this Guardian Australia report. “IHMS remains in frequent discussion with the signatories of the letter, and with the Department of Immigration and Border Protection about the matters raised in the letter,” it said.